1. Technical Field
The present invention relates to a vibration damping shaped aluminum extrusion including a pair of face plates which face each other and a rib connecting these face plates, which is, for example, a vibration damping shaped aluminum extrusion having a truss cross-section and is used for a structure or the like requiring the control of vibration, such as transport structure.
2. Background Art
Conventionally, a lightweight material having high rigidity is required as a structural member for high-speed railway vehicles such as Shinkansen train. Among metal materials, aluminum has a low specific gravity as compared with iron, can realize a high-rigidity cross-sectional profile by extrusion processing, and recently allows for application of a new welding technique capable of suppressing reduction in the strength of the welded part of friction stir welding or the like and therefore, a shaped aluminum extrusion has been widely used as a vehicle structure such as Shinkansen train, subway and existing railway line.
Examples of the shaped aluminum extrusions include a shaped aluminum extrusion called a hollow shaped aluminum extrusion, and examples of the hollow shaped aluminum extrusion include, for example, a truss shaped aluminum extrusion where two face plates are connected by ribs formed in a zigzag manner, and a ladder-shaped aluminum extrusion where two face plates are connected by ribs each substantially perpendicular to the face plates. The hollow shaped aluminum extrusion can increase the rigidity in a cross-section even if the thickness is small, and therefore, the hollow shaped aluminum extrusion is used for a floor surface, a side surface, a ceiling surface and the like of a vehicle.
As described above, the shaped aluminum extrusion is lightweight and can realize high rigidity but because of its low specific gravity, the shaped aluminum extrusion is liable to transmit vibration as compared with a conventionally employed steel-made structural member. Accordingly, in the case of using the shaped aluminum extrusion as a structural member of a vehicle, propagation of vibration noise from a wheel or a motor to a cabin (passenger room) must be more suppressed than the case of using a steel member.
On this account, various methods for controlling vibration of a shaped aluminum extrusion have been devised and, for example, there is a vibration damping shaped aluminum extrusion disclosed in Patent Document 1. The vibration damping shaped aluminum extrusion disclosed in Patent Document 1 is a shaped aluminum extrusion including a pair of face plates and one rib or two or more ribs each connecting the face plates, wherein a damping resin is provided on at least one surface of the rib.
It is demonstrated that according to the vibration damping shaped aluminum extrusion disclosed in Patent Document 1, the sound shielding effect can be enhanced without need for change in shape, such as increase of height, while minimizing the change in weight of the vibration damping shaped aluminum extrusion.    [Patent Document 1] Japanese Patent No. 2,640,078